[PATCH v7 3/4] PCI: brcmstb: Wait for Raspberry Pi's firmware when present

Nicolas Saenz Julienne
2020-04-29T16:48:49Z

xHCI's PCI fixup, run at the end of pcie-brcmstb's probe, depends on
RPi4's VideoCore firmware interface to be up and running. It's possible
for both initializations to race, so make sure it's available prior to
starting.

Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>

---

Changes since v6:
- Add more complete comment

drivers/pci/controller/pcie-brcmstb.c | 17 +++++++++++++++++
1 file changed, 17 insertions(+)

diff --git a/drivers/pci/controller/pcie-brcmstb.c b/drivers/pci/controller/pcie-brcmstb.c
index 6d79d14527a6..0b97b94c4a9a 100644
--- a/drivers/pci/controller/pcie-brcmstb.c
+++ b/drivers/pci/controller/pcie-brcmstb.c
@@ -28,6 +28,8 @@
#include <linux/string.h>
#include <linux/types.h>

+#include <soc/bcm2835/raspberrypi-firmware.h>
+
#include "../pci.h"

/* BRCM_PCIE_CAP_REGS - Offset for the mandatory capability config regs */
@@ -917,11 +919,26 @@ static int brcm_pcie_probe(struct platform_device *pdev)
{
struct device_node *np = pdev->dev.of_node, *msi_np;
struct pci_host_bridge *bridge;
+ struct device_node *fw_np;
struct brcm_pcie *pcie;
struct pci_bus *child;
struct resource *res;
int ret;

+ /*
+ * We have to wait for Raspberry Pi's firmware interface to be up as a
+ * PCI fixup, rpi_firmware_init_vl805(), depends on it. This driver's
+ * probe can race with the firmware interface's (see
+ * drivers/firmware/raspberrypi.c) and potentially break the PCI fixup.
+ */
+ fw_np = of_find_compatible_node(NULL, NULL,
+ "raspberrypi,bcm2835-firmware");
+ if (fw_np && !rpi_firmware_get(fw_np)) {
+ of_node_put(fw_np);
+ return -EPROBE_DEFER;
+ }
+ of_node_put(fw_np);
+
bridge = devm_pci_alloc_host_bridge(&pdev->dev, sizeof(*pcie));
if (!bridge)
return -ENOMEM;